As examples of an absorbent article that absorbs fluid, disposable diapers, sanitary napkins, and the like are used. These absorbent articles include an absorbent body 1 that is produced by forming pulp fibers into a predetermined shape.
This absorbent body 1 is formed by a fiber stacking apparatus 10a in a production line. FIG. 1 is a side view of the fiber stacking apparatus 10a partially showing a longitudinal section thereof. The fiber stacking apparatus 10a includes as the main body, a rotating drum 20 that rotates in one direction Dc. There are recessed shaped form dies 21 provided on the outer circumferential surface 20a of the rotating drum 20, which are configured to allow air suction from the bottom thereof. Further, there is also a distribution opening 31a of a duct 31 provided so as to oppose the outer circumferential surface 20a of the rotating drum 20. And from the distribution opening 31a, mixed air 3 discharged from the distribution opening 31a having pulp fiber 2 contained therein is discharged toward the outer circumferential surface 20a. 
Thus, when a form die 21 passes by the position of the distribution opening 31a as the rotating drum 20 rotates, mixed air 3 discharged from the distribution opening 31a is drawn in from the bottom of this form die 21. And along with this, owing to the suction force generated inside the form die 21, the pulp fibers 2 in the mixed air 3 stack in the form die 21 to form an absorbent body 1 (see patent document 1).    [Patent Document 1]    Japanese Patent Application Laid-open Publication No. 2006-132009